Tag Archives: batteries

The owner didn’t realize there were batteries in the backbox. And of course they were leaking. I removed the battery holder from the board and fortunately the board hadn’t been damaged by the alkaline. I replaced the RAM chip with an AnyPin NVRAM module so that forgotten batteries wouldn’t be an issue again.

The machine booted up fine after that. I did a quick “shop” job on the machine, replacing rubber rings, burned out lamps, and cleaning the playfield. There is a broken pop bumper cap, but I am unable to find an exact replacement.

Pop bumper caps, with target in the center and arrows/triangles around edge.

The corrosion was so bad that the battery holder nearly fell off the board when I started cleaning it up. The corrosion had eaten through the metal pins that hold the battery holder to the board. As you can see from the photo above, the corrosion was also affecting the nearby circuitry.

I finished removing the battery holder from the board and flushed the board with white vinegar and scrubbed with a toothbrush. The vinegar helps to neutralize the alkaline. After letting the board dry out for several hours, it still was able to boot up. I installed a remotely mounted battery holder on the inside of the backbox, where if the batteries leak in the future, it won’t damage anything.

I “shopped” the rest of the machine, replacing rubbers, cleaning the playfield, and replaced the bad bulbs. The machine is working great and looking great. I’ve now worked on more Funhouse pinball machines than any other model, breaking the previous record held by Star Trek: The Next Generation.

Fortunately, on the WPC-95 systems, the batteries are mounted on a separate piggy-backed board which saved the CPU board from certain death. But even so, the alkaline affected the cabinet switch connector located right next to the batteries.

The battery holder was removed and the RAM chip at U8 replaced with an anyPin NVRAM module that doesn’t require batteries.

The playfield was cleaned, all of the rubber parts were replaced, as well as the slingshot plastics. The machine is looking good and playing well.

Before powering up, the first thing I did was to remove the leaking NiCad battery from the MPU board. Fortunately, it hadn’t damaged the PCB traces. I replaced the RAM with an anyPin NVRAM module.

The machine wouldn’t boot when power was turned on. I checked the power supply first, since the power supplies in this era of Ballys are notorious for failing. All voltages were good.

The light on the MPU board flashed 7 times on power-up which indicated that most of the boot sequence was executing, but it was stopping just short of going into “Attract Mode”.

With my oscilloscope, I started probing around the MPU board. The processor was running and there was activity on the address and data buses. There was no activity on the IRQ (interrupt) line (pin 4 on U9). There are two sources (that I’m aware of) for interrupts. One is the display, the other is the AC zero crossing detector.

I checked the display interrupt generator, which is a 555 timer at U12. There were pulses on pin 3.

Next I checked the zero crossing detector and found no pulses there. The problem ended up being the 2.0K resistor (R113) at the input to the board, and is the top part of a voltage divider in conjunction with another 2K resistor at R16. Fortunately, Radio Shack still carries resistors (although the guys working there have no idea what a resistor is or what it does). We were able to get a 2.2K which is close enough.

All pinball machines made prior to about 2000 use some type of battery system for maintaining the settings and high scores. The batteries often leak and cause damage.

The “NV” in NVRAM stands for Non-Volatile, which means it will remember its contents with no power. It uses a ferroelectric technology where the RAM contents are stored in tiny magnetic charges.

anyPin NVRAM module by Pinball Classics

Since the Showdown, I’ve installed the modules in two of my customer’s machines.

The first machine was a Bally Bobby Orr Power Play in Windsor, Colorado. The CPU board in this machine had the original Ni-Cad rechargeable battery installed. It was leaking white alkaline from the ends. I de-soldered the battery from the board and installed the NVRAM module. It worked right at startup; no other configuration was needed.

The second machine was The Games by Gottlieb located in Brighton, Colorado. This uses the Gottlieb Systems 80A system. Like the Bally, it has a rechargeable battery. The battery itself didn’t look too bad after 30 years of use. But it would have started leaking soon. The other problem is the customer doesn’t leave the machine on long enough to charge it up. Powering up the pinball machine a couple of hours a week is not long enough to keep those batteries charged.

The old Gottlieb RAM chip was soldered on the CPU board, so I had to remove it, then installed the socket strips that come with the module. (That machine also had a bad display driver chip that needed replacing.) Everything worked flawlessly at power-up.

Williams and Stern pinball machines use AA batteries to remember their settings. They leak if you forget about them. I’ve got a customer with a Williams World Cup Soccer where the batteries leaked because the machine was in storage for a number of years. The alkaline from the batteries ate through the tin plating on the battery holder and now there is a very unreliable connection to the batteries.

I can’t recommend these anyPin NVRAM modules enough! Most of the machines I work on have some type of battery issue and this module is the long term solution.

The machine would immediate blow the fuse (less than 1 second) upon powering up. Fuse F4 supplies the 43 volt solenoid circuits which are prone to broken wires, shorted coils, etc. So, I expected to find a short somewhere on the playfield. I isolated the power supply by removing all of the connectors except for J2 (cabinet) which supplies the wall AC power to the power supply, but this connector also supplies solenoid power to the knocker and the coin door. The fuse still blew. I checked the cabinet wiring to make sure there was no short, then focused on the power supply itself.

It turned out to be a shorted bridge rectifier between the AC and the minus (-). I brought the power supply back to my shop for repair. I looked up the part number for the bridge and found it on Marco’s site. For better or worse, the bridge I received was slightly larger. Not only were the pins further apart, it was also thicker.

New bridge rectifier (black square) above an original working bridge rectifier just below it.

This posed a problem as there are two bridge rectifiers in the circuit and both are mounted on the bottom side of the PCB and are heat-sinked against a metal bar on the power supply chassis. If one is thicker than the other, one will be heat-sinked, the other will not.

I decided to shift the bar over, so that existing bridge would contact the bar and the new bridge would go directly to the chassis.

With the metal bar, both rectifiers will contact the chassis when the board is remounted.

I added some new heatsink grease to both bridges. I powered the circuit and all was fine. This power supply was only used on two machines, KISS and Space Invaders.

Back at the customer’s location, the game powered up and worked fine. I replaced a few burned out bulbs. The NiCad RAM backup battery mounted on the CPU board has partially failed. I am debating whether to replace it with a 1 farad super cap, or the typical 3 cell AA holder. The super cap requires the machine to be powered up periodically so that it can recharge. The AA batteries don’t require recharging, but there is no nice place to put the battery pack and they have to replaced every few years.

Reviews

"Randy is a true professional with amazing knowledge of electrical wiring, programming, boards and mechanical workings. He has always arrived promptly with all the tools and parts needed to efficiently complete the jobs. Randy has worked on my three Williams machines (Taxi, T2, and Funhouse) and based on his previous work, I am confident he could solve any future issue." --Greg M., Louisville, CO

"Randy was there an hour and found the problem and also a couple other potential issues. He was very professional and knowledgeable and I feel he has the ability to troubleshoot anything pinball or anything electronic for that matter." --Craig H., Broomfield, CO

"Randy just left here and after over 20 years I now have a jukebox that works."--Jeff, Aurora, CO.

"Randy is always very professional and extremely knowledgeable about the work that needs to be done. He is the best out there that can be found for pinball and juke box repairs."--Larry, Sidney, NE.